3. Longest Substring Without Repeating Characters

• categories: Code, Interview Question, leetcode, Medium
• source: https://leetcode.com/problems/longest-substring-without-repeating-characters
• topics: Sliding Window

Given an array of positive integers nums and a positive integer target, return the minimal length of a  subarray  whose sum is greater than or equal to target. If there is no such subarray, return 0 instead.

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        current_window_size = 0
        used_chars = set()
        ans = 0
        for i in range(len(s)):
            while s[i] in used_chars:
                used_chars.remove(s[i - current_window_size])
                current_window_size -= 1
            used_chars.add(s[i])
            current_window_size += 1
            ans = max(ans, current_window_size)
               
        return ans